New compounds having a protective activity against toxins with intracellular activity

ABSTRACT

The present invention concerns a new family of 2,3-dihydroquinazolin-4(1H)-one compounds of general formula (I), and the use thereof as inhibitors of the toxic effects of toxins with intracellular activity, such as ricin or Shiga toxin, for example, using retrograde transport to intoxicate cells.

The subject of the present invention is a new family of 2,3-dihydroquinazolin-4(1H)-one compounds and the use thereof as inhibitors of the toxic effects of toxins with intracellular activity, for instance ricin, using retrograde transport to poison cells.

Toxins with intracellular activity which use retrograde transport represent a major public health problem and are associated with more than one million deaths each year throughout the world. These toxins are in particular ricin (produced in the seeds of the Ricinus communis plant), Shiga toxin and Shiga-like toxins (Stas) produced by Shigella dysenteriae (Stx) and E. coli (Stx1 and Stx2), cholera toxin (Ctx Vibrio cholerae responsible for cholera), pertussis toxin (Bordetella pertussis, the agent responsible for whooping cough), subtilase cytotoxin and thermolabile enterotoxin (E. coli).

Ricin is a 66 kDa glycoprotein composed of two polypeptide chains linked by a disulfide bridge (FIG. 1A). The B chain (RTB, lectin of 262 residues) allows the toxin to bind to cell membrane glycolipids and glycoproteins and ensures its entry into the cell (FIG. 1A). The A chain (RTA, 267 amino acids) provides the N-glycosidase enzymatic function of ricin, catalyzes the removal of adenine 4324 of the 28S RNA of the targeted cells and causes the arrest of protein synthesis.

Shiga toxins include the Shiga toxin (Stx) produced by Shigella dysenteriae and the Shiga-like 1 (Stx1) and 2 (Stx2) toxins produced by the enterohemorrhagic strains of E. coli. The Stx and Stx1 toxins are 99% identical, while Stx1 and Stx2 share only 56% identity of their amino acid sequence. The A subunit of the toxin (StxA) carries the same enzymatic activity as ricin and identically targets the 28S RNA (FIG. 1B). The B subunit (StxB), which is in pentameric form, allows binding of the toxin with the cell via its interaction with globotriaosylceramide Gb3, which ensures its internalization and its intracellular trafficking.

After binding to its membrane receptors, ricin is internalized into these cells via multiple endocytosis pathways and reaches the trans-Golgi network where it is conveyed to the endoplasmic reticulum (ER) by retrograde transport (FIG. 2A). Shiga toxins are, for their part, internalized via a single endocytosis pathway and also reach the Golgi apparatus and then the endoplasmic reticulum (FIG. 2B).

The toxins are then partially unfolded and the A chain/subunit is translocated into the cytosol (Lord, J. M. et al., Biochemical Society Transactions 2003, 31, 1260). The ultimate step of the action of these toxins thus takes place in the cell cytoplasm; the toxins bind to ribosomes with great efficiency and cleave adenine 4324 of the 28S RNA of the 60S subunit of the ribosome. This depurination of the 28S RNA causes the arrest of protein synthesis and leads to cell death.

To counter the threat posed by these toxins, several types of antitoxins have been developed: neutralizing antibodies, enzymatic activity inhibitors (small molecules, substrate analogs), soluble receptor mimetics and chemical compounds which act on the cells targeted by the toxin:

-   -   Small molecules which inhibit the enzymatic activity of ricin         (Miller, D. et al., J. Med. Chem 2002, 45, 90 and Yan, X. et         al., J. Mol. Biol. 1997, 266, 1043).     -   Small molecules which inhibit the enzymatic activity of Stx         (Brigotti M. et al., Nucleic Acids Res. 2000, 28 (12), 2383).     -   RNA derivatives: since ricin recognizes a very precise sequence         in the 28S RNA, the SRL loop (Sarcin-Ricin Loop), inhibitors         have been designed on the basis of this nucleotide sequence         (Schramm et al. Biochemistry 2001, 40 (23), 6845; Roday, S. et         al., Biochemistry 2004, 43, 4923; Hesselberth, J. R. et al., J.         Biol. Chem. 2000, 275, 4937, Fan, S. et al., World J.         Gastroenterol. 2008, 14, 6360).     -   Antibodies directed against ricin (Lemley, P. V. et al.,         Hybridoma 1994, 13, 417; Guo, J. W. et al., Hybridoma 2005, 24,         263; Pelat, T. et al., BMC Biotechnol. 2009, 9, 60).     -   Antibodies directed against Stx (Sheoran A. S. et al., Infect         Immun. 2005, 73, 4607-13; Tzipori S. et al., Clin. Microbiol.         Rev. 2004 17, 926-41).     -   Soluble mimetics of ricin receptors (Perera L. P. et al., J Clin         Microbiol. 1988, 26, 2127-31; Smith M. J. et al., Infect Immun.         2006, 74, 6992-8).     -   Soluble mimetics of Stx receptors (Armstrong G. D. et al., J.         Infect. Dis. 1995, 171, 1042-5; Trachtman H. et al., JAMA 2003,         290, 1337-44; Kitov P. I. et al., Nature 2000, 403, 669-72;         Nishikawa K. et al., PNAS 2002, 99, 7669-74; Mulvey G. L. et         al., J. Infect. Dis. 2003, 187, 640-9; Watanabe et al., J.         Infect. Dis. 2004, 189, 360-8).     -   Vaccine approach for controlling the effects of ricin: a certain         number of vaccines have been described in particular in         scientific patents and publications. They claim protection         against ricin via the administration of an immunogenic amount of         RTA or RTB derivatives.     -   Vaccine approach for controlling the effects of Stx: a vaccine         that is effective in humans should result in the production of         antibodies preventing the colonization of bacteria in the         intestinal tract or neutralizing the Shiga toxins produced, in         order to prevent the development of hemolytic uremic syndrome.         Such a vaccine is not available at the current time, even though         research studies are currently being carried out in this         direction.

Over the past few years, research for new molecules aimed at blocking intracellular trafficking of toxins with intracellular activity has accelerated. The main advantage of molecules of this type is their broad-spectrum activity since these molecules can efficiently protect cells against the various toxins which use the retrograde pathway.

However, these molecules, such as Brefeldin A (Donta S. T. et al., J. Infect. Dis. 1995 171, 721-4), Exo2 (Spooner R. A. et al., Biochem J. 2008, 414, 471-84; Yarrow J. C. et al., C.C.H.T.S. 2003, 6, 279-86), Golgicide (Saenz J. B. et al., Nat. Chem. Biol. 2009, 5, 157-65) and others (Saenz J. B. et al., Infect. Imm. 2007, 75, 4552-61), even though they protect cells against the action of toxins with intracellular activity, are themselves cytotoxic since they target key functions of cell homeostasis and cannot therefore be used for therapeutic purposes.

Other molecules have been identified, in particular by high-throughput screening, as the inhibitor of the action of ricin and/or of Stxs: compounds 134 and 75 (Saenz J. B. et al., Infect. Imm. 2007, 75, 4552-61) (see the scheme hereinafter). The cellular target of these molecules remains unknown; they appear to block ricin and Stx transport inside the cells. However, these compounds do not protect A549 human pulmonary epithelial cells and none of these molecules has shown a protective effect in animals. Furthermore, these molecules modify the morphology of the Golgi apparatus, thereby indicating, on the one hand, a different mechanism of action and, on the other hand, an intrinsic toxicity of the compounds.

High-throughput screening has also made it possible to identify the compounds Retro-1 and Retro-2 (EP2145873, WO2009/153457, WO2009/153665, Stechmann B. et al., Cell 2010, 141, 231-42) as ricin and/or Stx inhibitors; these compounds are capable of protecting A549 human pulmonary epithelial cells; in addition Retro-2 has shown efficacy in animals.

Another research team has identified new molecules which protect against ricin and Stxs, also during high-throughput screening on Vero cells (Wahome P. G. et al., Toxicon 2010, 56, 313-23). These compounds (CID 644401, CID 5737931 and CID 18576762) do not appear to be as active (EC50 between 25 and 60 μM) as the Retro-1 and Retro-2 compounds and their mode of action remains unknown.

A. Inhibitors with an Identified Cell Target

B. Inhibitors of which the Cell Target is Unknown

Small Molecules with Intracellular Activity which Inhibit the Action of Ricin and/or of Stxs

Very recently, the team of Park et al. [Park et al. Chemical Structure of Retro-2, a Compound That Protects Cells against Ribosome-Inactivating Proteins. Nature Scientific Reports. 2012. 2; 631] has studied the chemical structure of Retro-2 and has demonstrated the spontaneous cyclization of this compound and shown that it is in this cyclized form that Retro-2 exercises a protective activity on cells against the toxins.

In the context of its research on compounds which block retrograde transport and more particularly of studies on compounds derived from cyclized Retro-2, carried out in parallel with the abovementioned studies, the applicant has identified a new family of compounds derived from 2,3-dihydroquinazolin-4(1H)-one which exhibit a biological activity greater than that of cyclized Retro-2 and therefore a marked value for the prevention and/or treatment of poisoning with at least one toxin with an intracellular mode of action using retrograde transport to infect mammalian eukaryotic cells.

Thus, the present invention relates to compounds of general formula (I):

wherein R¹ represents a hydrogen atom, a halogen atom or an alkoxy radical having from 1 to 3 carbon atoms; R² represents:

-   -   a phenyl radical, optionally substituted with: a phenyl radical,         a —CF₃ group, a halogen atom, an —SO₂-phenyl group or an —S—X or         —O—X group, X being an alkyl radical having from 1 to 4 carbon         atoms, preferably a methyl radical, an alkoxy having from 1 to 4         carbon atoms or a PEG of formula —(CH₂—CH₂—O)_(n)—R with n being         1 to 10, preferably n is 1, and R represents a hydrogen atom or         a methyl radical, preferably R is a methyl radical, or a —CO—Y         or —CO—O—Y group, Y being chosen from a hydrogen atom, an alkyl         radical having from 1 to 4 carbon atoms, a phenyl ring or an         allyl (—CH₂—CH═CH₂) group;         -   a heterocycle or a heterobicycle having from 5 to 10 atoms             comprising one or two nitrogen atoms, preferably a pyridine             radical;         -   an adamantyl ring, optionally substituted with a hydroxyl             function;             R³ represents:     -   an aromatic heterocycle having 5 or 6 atoms, which may be chosen         from a thiophene, furan, pyrrole, pyrroline, pyrrolidine,         dioxolane, oxazole, thiazole, imidazole, imidazoline,         imidazolidine, pyrazole, isoxazole, isothiazole, pyran,         pyridine, piperidine, dioxane, morpholine, pyridazine,         pyrimidine or pyrazine ring, preferably a thiophene or pyridine         ring;     -   said heterocycle being substituted with:         -   an alkyl radical having from 1 to 3 carbon atoms, preferably             a methyl radical;         -   a halogen atom;         -   a phenyl radical optionally substituted with an alkoxy             radical having from 1 to 3 carbon atoms, a —CN group, an             —NO₂ group or a —COX or —COOX group with X an alkyl radical             having from 1 to 4 carbon atoms, or a combination of these             substituents, preferably a methyl radical;         -   a —SY group, Y being an alkyl radical having from 1 to 4             carbon atoms or a phenyl radical;         -   a —CN group;         -   a —CH₂—N₃ group;         -   an aromatic heterocycle having 5 or 6 atoms, which may be             chosen from a furan, thiophene, pyrrole, pyrroline,             pyrrolidine, dioxolane, oxazole, thiazole, imidazole,             imidazoline, imidazolidine, pyrazole, isoxazole,             isothiazole, pyran, pyridine, piperidine, dioxane,             morpholine, pyridazine, pyrimidine or pyrazine ring,             preferably said heterocycle having 5 or 6 atoms is a             thiophene, a pyridine, a furan or a thiazole; optionally             substituted with at least one alkyl radical having from 1 to             3 carbon atoms and/or a —CH₂—N₃ group;     -   a phenyl radical; optionally substituted with an alkoxy radical         having from 1 to 3 carbon atoms or an NMe₂ group;         R⁴ represents a hydrogen atom or a methyl radical;         with the exception of the compound such that R¹ is a hydrogen         atom, R² a phenyl radical, R³ a 5-methylthiophen-2-yl radical         and R⁴ a hydrogen atom,         and the pharmaceutically acceptable salts thereof.

The present invention relates to the compounds of general formula (I) as such and also to the use thereof for the prevention and/or treatment of disorders induced by toxins with intracellular activity using retrograde transport.

The present invention also relates to a method for preventing and/or treating disorders induced by toxins with intracellular activity using retrograde transport and comprising the administration of an effective amount of at least one compound of general formula (I).

Preferably, the following compounds of general formula (I):

-   3-(4-chlorophenyl)-2-(5-methylthiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one;     R¹═—H; R²=pyridinyl; R³=3,4-dimethoxyphenyl and R⁴═—H;     R¹═—H; R²=methoxyphenyl; R³=pyridinyl and R⁴═—H;     R¹═—H; R²=phenyl; R³=6-methyl-2-pyridinyl and R⁴═—H;     R¹═—H; R²=methoxyphenyl; R³=dimethylaminophenyl and R⁴═—H;     R¹═—H; R²=phenyl; R³=furanyl and R⁴═—H;     R¹═—H; R²=phenyl-phenyl; R³=methoxyphenyl and R⁴═—H;     R¹═—H; R²=phenyl; R³=dimethylaminophenyl and R⁴═—H;     R¹═—H; R²=phenyl; R³=phenyl and R⁴═—H;     R¹═—H; R²=4-chlorophenyl; R³=5-methyl-2-thienyl and R⁴═—H;     R¹═—H; R²=phenyl; R³=methoxyphenyl and R⁴═—H;     and those such that R² is a substituted phenyl and R³ a furan ring,     a substituted phenyl or a pyridine;     as such are excluded from the subject of the present invention; on     the other hand, the use thereof for therapeutic purposes, in     particular for the prevention and/or treatment of disorders induced     by toxins with intracellular activity using retrograde transport is     indeed a subject of the present invention.

The term “pharmaceutically acceptable salt of the compounds of general formula (I)” is intended to mean the hydrochlorides, hydrobromides, sulfates or bisulfates, phosphates or hydrogen phosphates, acetates, oxalates, benzoates, succinates, fumarates, maleates, lactates, citrates, tartrates, gluconates, methanesulfonates, benzenesulfonates and para-toluenesulfonates.

The term “halogen atom” is intended to mean the chemical elements of group VII of the Periodic Table of the elements, in particular fluorine, chlorine, bromine and iodine.

The term “alkyl radical having from 1 to 3 or 4 carbon atoms” denotes a linear or branched hydrocarbon-based radical; mention may, for example, be made of methyl, ethyl, propyl, isopropyl or tert-butyl.

The term “alkoxy radical having from 1 to 3 or 4 carbon atoms” is intended to mean an —O_(n)H_(2n+1) radical, n being an integer between 1 and 3 or 4; mention may, for example, be made of the methoxy, ethoxy, propyloxy or isopropyloxy radical. Preferably, n is 1.

More particularly, the compounds of general formula (I) are chosen from table I hereinafter:

Molecule Compound Structure Name RN-1-013 1

2-(3-Methoxyphenyl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-019 2

2-(4-(Dimethylamino)phenyl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-1-021 3

2,3-Diphenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1-027 4

2-(4-Methoxyphenyl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-066 5

2-(3-Methylthiophen-2-yl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-1-067 6

2-(4-Methylthiophen-2-yl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-1-068 7

2-(5-Ethylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-086 8

3-((5R,7S)-3-Hydroxyadamantan-1-yl)- 2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-100 9

2-(5-Bromothiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-118 10

2-(5-Methylthiophen-2-yl)-3-(pyridin-3- yl)-2,3-dihydroquinazolin-4(1H)-one RN-1-120 11

2-(5-Methylthiophen-2-yl)-3-(pyridin-4- yl)-2,3-dihydroquinazolin-4(1H)-one RN-1-132 12

2-(5-Methylthiophen-2-yl)-3- (pyrimidin-4-yl)-2,3-dihydroquinazolin- 4(1H)-one RN-1-148 13

3-Phenyl-2-(5-phenylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-149 14

3-([1,1′-Biphenyl]-4-yl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-151 15

2-(5-Methylthiophen-2-yl)-3-(3- (trifluoromethyl)phenyl)-2,3- dihydroquinazolin-4(1H)-one RN-1-162 16

8-Methyl-2-(5-methylthiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-1-173 17

2-(5-(Methylthio)thiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-1-174 18

2-([2,2′-Bithiophen]-5-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-175 19

3-Phenyl-2-(5-(pyridin-2-yl)thiophen-2- yl)-2,3-dihydroquinazolin-4(1H)-one RN-1-176 20

2-(5-(Furan-2-yl)thiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-1-177 21

2-(5-(2-Methylthiazol-4-yl)thiophen-2- yl)-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-2-120 22

3-(4-Fluorophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-137 23

3-(2-Fluorophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-161 24

6-Methoxy-2-(5-methylthiophen-2-yl)- 3-phenyl-2,3-dihydroquinazolin-4(1H)- one RN-2-162 25

6-Fluoro-2-(5-methylthiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-2-163 26

7-Fluoro-2-(5-methylthiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-2-177 27

3-(4-Bromophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-178 28

3-(3-Bromophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-180 29

3-(4-Chlorophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-181 30

3-(3-Chlorophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-183 31

3-(2-(Methylthio)phenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-182 32

3-(2-Chlorophenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-199 33

6-Iodo-2-(5-methylthiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-3-121 34

6-Fluoro-2-(5-(2-methylthiazol-4- yl)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-181 35

1-Methyl-2-(5-methylthiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-1-186 36

1-Methyl-3-phenyl-2-(5- phenylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-192 37

1-Methyl-3-phenyl-2-(5-(pyridin-2- yl)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-196 38

1-Methyl-2-(5-(methylthio)thiophen-2- yl)-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1-197 39

2-([2,2′-Bithiophen]-5-yl)-1-methyl-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-2-001 40

2-(5-(Furan-2-yl)thiophen-2-yl)-1- methyl-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-2-005 41

2-(5-Ethylthiophen-2-yl)-1-methyl-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-2-015 42

1-Methyl-2-(5-(2-methylthiazol-4- yl)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-016 43

2-(5-Bromothiophen-2-yl)-1-methyl-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-2-019 44

1-Methyl-3-phenyl-2-(5- (phenylthio)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-029 45

2-(5-(3,4-Dimethoxyphenyl)thiophen-2- yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-032 46

1-Methyl-2-(5-(3-nitrophenyl)thiophen- 2-yl)-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-2-034 47

2-(5-(Furan-3-yl)thiophen-2-yl)-1- methyl-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-2-049 48

Methyl 4-(5-(1-methyl-4-oxo-3-phenyl- 1,2,3,4-tetrahydroquinazolin-2- yl)thiophen-2-yl)benzoate RN-2-050 49

2-(5-(4-Acetylphenyl)thiophen-2-yl)-1- methyl-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-2-053 50

1-Methyl-3-phenyl-2-(5-(3,4,5- trimethoxyphenyl)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-057 51

1-Methyl-2-(5-(4-methyl-3- nitrophenyl)thiophen-2-yl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-2-059 52

4-(5-(1-Methyl-4-oxo-3-phenyl-1,2,3,4- tetrahydroquinazolin-2-yl)thiophen-2- yl)benzonitrile RN-3-012 53

5-(1-Methyl-4-oxo-3-phenyl-1,2,3,4- tetrahydroquinazolin-2-yl)thiophene-2- carbonitrile RN-3-066 54

3-(2-Chlorophenyl)-1-methyl-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-067 55

3-(2-Iodophenyl)-1-methyl-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-068 56

3-(2-Methoxyphenyl)-1-methyl-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-069 57

1-Methyl-3-(2-(methylthio)phenyl)-2- (5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-070 58

3-(2-Fluorophenyl)-1-methyl-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-089 59

3-([1,1′-Biphenyl]-2-yl)-1-methyl-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-098 60

1-Methyl-2-(5-methylthiophen-2-yl)-3- (2-(phenylsulfonyl)phenyl)-2,3- dihydroquinazolin-4(1H)-one RN-3-122 61

6-Fluoro-1-methyl-2-(5-(2- methylthiazol-4-yl)thiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)- one RN-3-061 62

2-(5-(Azidomethyl)thiophen-2-yl)-1- methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one VP37 63

2-(5-(2-(Azidomethyl)thiazol-4- yl)thiophen-2-yl)-1-methyl-3- phenyl-2,3-dihydroquinazolin-4(1H)- one VP153 64

2-(5-(2-(Azidomethyl)thiazol-4- yl)thiophen-2-yl)-6-fluoro-1-methyl- 3-phenyl-2,3-dihydroquinazolin- 4(1H)-one VP22 65

3-(2-Benzoylphenyl)-1-methyl-2-(5- (2-methylthiazol-4-yl)thiophen-2- yl)-2,3-dihydroquinazolin-4(1H)-one VP104 66

3-(2-Benzoylphenyl-6-fluoro-1- methyl-2-(5-(2-methylthiazol-4- yl)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one KH071-4 67

Allyl 2-(1-methyl-2-(5- methylthiophen-2-yl)-4-oxo-1,4- dihydroquinazolin-3(2H)- yl)benzoate KH093-4 68

3-(2-(2-Methoxyethoxy)phenyl)-1- methyl-2-(5-methylthiophen-2-yl)- 2,3-dihydroquinazolin-4(1H)-one KH112-2 69

2-(1-Methyl-2-(5-methylthiophen-2- yl)-4-oxo-1,4-dihydroquinazolin- 3(2H)-yl)benzoic acid

According to one preferred embodiment of the invention, the compounds of general formula (I) are such that:

-   -   R¹ is as previously defined: i.e. R¹ represents a hydrogen atom,         a halogen atom, an alkoxy radical having from 1 to 3 carbon         atoms; preferably, R¹ is a hydrogen atom or a halogen atom;         preferably, R¹ is bonded to carbon C7 of the quinazolinone ring;     -   R² is a phenyl ring, optionally substituted with: a phenyl         radical, a halogen atom, an —SO₂-phenyl group, an —S—X or —O—X         group, X being an alkyl radical having from 1 to 4 carbon atoms;         preferably a methyl radical, an alkoxy having from 1 to 4 carbon         atoms, or a PEG of formula —(CH₂—CH₂—O)_(n)—R with n being 1 to         10, preferably n is 1, and R is a hydrogen atom or a methyl         radical, preferably R is a methyl radical, or a —CO—Y or —CO—O—Y         group, Y being chosen from a hydrogen atom, an alkyl radical         having from 1 to 4 carbon atoms, a phenyl ring or an allyl         (—CH₂—CH═CH₂) group;     -   R³ represents a thiophene ring substituted on C5′ of the         thiophene, the quinazolinone ring being bonded to C2′ of the         thiophene, with:     -   an alkyl radical having from 1 to 3 carbon atoms, preferably a         methyl radical;     -   a halogen atom;     -   a phenyl radical optionally substituted with an alkoxy radical         having from 1 to 3 carbon atoms, a —CN group, an —NO₂ group or a         —COX or —COOX group with X an alkyl radical having from 1 to 4         carbon atoms, or a combination of these substituents, preferably         a methyl radical;     -   a —SY group, Y being an alkyl radical having from 1 to 4 carbon         atoms or a phenyl radical;     -   a —CN group;     -   a —CH₂—N₃ group;     -   an aromatic heterocycle having 5 or 6 atoms, which may be chosen         from a furan, thiophene, pyrrole, pyrroline, pyrrolidine,         dioxolane, oxazole, thiazole, imidazole, imidazoline,         imidazolidine, pyrazole, isoxazole, isothiazole, pyran,         pyridine, piperidine, dioxane, morpholine, pyridazine,         pyrimidine or pyrazine ring, preferably said heterocycle having         5 or 6 atoms is a thiophene, a pyridine, a furan or a thiazole;         optionally substituted with at least one alkyl radical having         from 1 to 3 carbon atoms and/or a —CH₂—N₃ group;     -   R⁴ is as previously defined, i.e. it represents a hydrogen atom         or a methyl radical;         with the exclusion of         3-(4-chlorophenyl)-2-(5-methylthiophen-2-yl)-2,3-dihydro-quinazolin-4(1H)-one         and of the compound such that R¹ is a hydrogen atom, R² a phenyl         radical, R³ a 5-methylthiophen-2-yl radical and R⁴ a hydrogen         atom.

The chemical structure which follows represents the numbering of the carbons used to define the position of the substitutions in the compounds of this preferred embodiment of the invention

The preferred compounds according to this embodiment of the invention are those chosen from compounds 7, 9, 13, 14, 16 to 28 and 30 to 69.

According to one preferred variant of the preceding embodiment, R² is a phenyl ring substituted on its carbon C2″ (compounds 23, 31, 32, 54 to 60 and 65 to 69) and/or R⁴ is a methyl radical (compounds 35 to 69).

According to another preferred embodiment of the invention, the compounds of general formula (I) are such that:

-   -   R¹ is a hydrogen atom or a fluorine atom;     -   R² is phenyl ring optionally substituted with: a chlorine,         iodine or fluorine atom, an —OCH₃, —SCH₃ or —SO₂-phenyl radical         or a phenyl;     -   R³ is a thiophene radical substituted with a methyl, ethyl,         phenyl, —SCH₃, 2-thiophene, 2-furan, 3-furan, 2-pyridine or         4-(2-Me thiazole) radical, a bromine atom or S-phenyl, and     -   R⁴ is a hydrogen atom or a methyl radical;         with the exclusion of the compound such that R¹ is a hydrogen         atom, R² a phenyl radical, R³ a 5-methylthiophen-2-yl radical         and R⁴ a hydrogen atom, and their pharmaceutically acceptable         salts thereof.

The preferred compounds according to this other embodiment of the invention are those chosen from 7, 9, 13, 17, 18, 19, 20, 21, 25, 31, 32, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 47, 54, 55, 56, 57, 58, 59, 60 and 61.

The compounds of general formula (I) for which R⁴ is a hydrogen atom are obtained from the imine-type compounds which are analogs of Retro-2 (see application EP 2 145 873) by cyclization in a basic medium (route A) or directly by reaction of the anthranilamide with the aldehyde (route B):

The compounds of general formula such that R⁴ is a methyl substituent as represented opposite:

are obtained by deprotonation of the amine in position 1 and trapping of the anion with methyl iodide,

where R¹, R² and R³ are defined as previously.

Some of the compounds according to the invention, in particular compounds 45, 46, 47, 48, 49, 50, 51 and 52, were synthesized via the route described hereinafter:

or by coupling of compound 43 with PhSH in the presence of Pd₂dba₃ (0.1 equiv.), dppf (0.15 equiv.) and tBuOK (2 equiv.) in dioxane, for 1 h at 140° C. in a microwave (compound 44) or ZnCN₂ in the presence of Pd₂dba₃ (0.05 equiv.) and dppf (0.1 equiv.) in DMF, for 1 h at 150° C. in a microwave (compound 53).

The compounds according to the invention are pharmacologically active substances and are of interest by virtue of their inhibitory effect on toxins with an intracellular mode of action, in particular ricin.

The use of the compounds of general formula (I), including the various embodiments and the preferred variants thereof, is particularly advantageous for preventing and/or treating disorders caused by toxins with an intracellular mode of action using retrograde transport to poison mammalian eukaryotic cells.

More specifically, the toxins with an intracellular mode of action are: in particular ricin (produced in the seeds of the Ricinus communis plant), Shiga toxin and Shiga-like toxins (Stas) produced by Shigella dysenteriae (Stx) and E. coli (Stx1 and Stx2), cholera toxin (Ctx from Vibrio cholerae responsible for cholera), pertussis toxin (Bordetella pertussis, which is the agent responsible for whooping cough), subtilase cytotoxin and thermolabile enterotoxin (E. coli).

The use of the compounds according to the invention proves to be effective whether the subject ingests or inhales the toxin or whether the subject is injected with the toxin.

Thus, the compounds according to the invention may be used for preventing and/or treating the poisoning of mammalian eukaryotic cells by toxins with an intracellular mode of action.

Concretely, a toxin such as ricin, when it is inhaled, produces signs of ocular irritation (burning sensation, watering of the eyes, more or less severe conjunctivitis) and pharyngeal irritation and also more or less marked respiratory irritation: cough, dyspnea, pulmonary edema which can result in acute respiratory distress syndrome (ARDS). It should be noted that there is a risk of anaphylactic reaction. The lethal dose is 1 mg/kg of bodyweight (Ministry of Health, France).

Thus, the invention relates to the use of a compound of general formula (I) for preventing and/or treating poisonings with ricin or with other toxins with an intracellular mode of action and protecting eukaryotic cells, in particular epithelial, ocular, pharyngeal, tracheal, bronchial, skin and muscle cells, in particular pulmonary and digestive, preferably intestinal, epithelial cells, of mammals, preferably of humans, against these poisonings.

The invention also relates to pharmaceutical compositions or medicaments comprising one or more compounds of general formula (I) in a pharmaceutically acceptable carrier.

The term “pharmaceutically acceptable” is intended to mean compatible with administration to a subject, preferably a mammal, by any route of administration.

Those skilled in the art will be able to adjust the formulation of the compounds of general formula (I) according to the physicochemical properties thereof and the route of administration thereof.

The medicament may be administered via the oral (in particular in the buccal cavity or by sublingual administration), parenteral, pulmonary, ocular, nasal, etc., route. Other methods of administration that can be envisioned comprise the intraperitoneal (i.p), intravenous (i.v.), subcutaneous (s.c.), intramuscular (i.m.), transcutaneous, transdermal, intracathecal, epidural, submucosal, or nasal or pulmonary inhalation route.

The methods of administration of the compounds of general formula (I) that are preferred are those which use the airway route (nasal or pulmonary inhalation), the oral route (ingestion), the parenteral route or the local (topical) route.

The present invention thus relates to compositions, in particular pharmaceutical compositions, comprising at least one compound of general formula (I) according to the invention and, optionally, a pharmaceutically acceptable carrier, stabilizing excipients and adjuvants conventionally used.

The amount of compound of general formula (I) to be administered to the mammal depends on this compound's own activity, it being possible for said activity to be measured by means which are set out in the examples. This amount also depends on the seriousness of the pathological condition to be treated, in particular on the amount of toxin absorbed and on the route by which it was absorbed; finally, it depends on the age and weight of the individual to be treated.

In addition to the arrangements which precede, the invention also comprises other arrangements that will emerge from the description which follows, which refers to exemplary embodiments of the present invention, and also to the appended figures in which:

FIG. 1 represents the crystallographic structures of ricin (A, the name of which in the crystallographic structure database is pdb 2AAI) and of Stx2 (B, pdb 1R4P).

FIG. 2 illustrates diagrammatically the entry and the intracellular trafficking of ricin (A) and of Shiga toxins (B).

FIG. 3 is a diagrammatic representation of the cell test carried out in the experimental section.

FIG. 4 illustrates the method for determination of R and of the EC₅₀ values carried out in part II of the examples.

FIG. 5 illustrates the method for calculating the IC₅₀ carried out in part II of the examples; the toxicity curves are produced in the absence of inhibitor (Control) and then in the presence of inhibitor at various concentrations.

EXAMPLES I. Synthesis of Compounds According to the Invention

The compounds of general formula (I) which follow are prepared according to the reaction scheme which follows:

Protocol: 2-aminobenzamide (4.71 mmol), THF (23 ml, 0.2M) and then the aldehyde (4.71 mmol) and para-toluenesulfonic acid (10 mol %, 0.5 mmol) are added to a tube which is sealed. The solution is heated at 75° C. and stirred at this temperature until the starting products have completely disappeared (monitored by thin layer chromatography, typically a reaction time of overnight). After cooling to room temperature, silica is added and the THF is evaporated off Purification by silica gel chromatography followed by evaporation provides the expected products in the form of solids.

TABLE II Cyclic molecules of 2,3-dihydroquinazolin-4(1H)-one type LC/ Molecule Compound Name Yield MS ¹H ¹³C RN-1- 1 2-(3-Methoxyphenyl)-3-phenyl-2,3- 88% x x x 013 dihydroquinazolin-4(1H)-one RN-1- 2 2-(4-(Dimethylamino)phenyl)-3- 77% x x x 019 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 3 2,3-Diphenyl-2,3- 84% x x x 021 dihydroquinazolin-4(1H)-one RN-1- 4 2-(4-Methoxyphenyl)-3-phenyl-2,3- 78% x x x 027 dihydroquinazolin-4(1H)-one RN-1- 5 2-(3-Methylthiophen-2-yl)-3- 85% x x x 066 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 6 2-(4-Methylthiophen-2-yl)-3- 65% x x x 067 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 7 2-(5-Ethylthiophen-2-yl)-3-phenyl- 77% x x x 068 2,3-dihydroquinazolin-4(1H)-one RN-1- 8 3-((5R,7S)-3-Hydroxyadamantan- 81% x x x 086 1-yl)-2-(5-methylthiophen-2-yl)- 2,3-dihydroquinazolin-4(1H)-one RN-1- 9 2-(5-Bromothiophen-2-yl)-3- 91% x x x 100 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 10 2-(5-Methylthiophen-2-yl)-3- 34% x x x 118 (pyridin-3-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1- 11 2-(5-Methylthiophen-2-yl)-3- 64% x x x 120 (pyridin-4-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1- 12 2-(5-Methylthiophen-2-yl)-3- 53% x x x 132 (pyrimidin-4-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1- 13 3-Phenyl-2-(5-phenylthiophen-2- 86% x x x 148 yl)-2,3-dihydroquinazolin-4(1H)- one RN-1- 14 3-([1,1′-Biphenyl]-4-yl)-2-(5- 73% x x x 149 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1- 15 2-(5-Methylthiophen-2-yl)-3-(3- 68% x x x 151 (trifluoromethyl)phenyl)-2,3- dihydroquinazolin-4(1H)-one RN-1- 16 8-Methyl-2-(5-methylthiophen-2- 99% x x x 162 yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1- 17 2-(5-(Methylthio)thiophen-2-yl)-3- 82% x x — 173 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 18 2-([2,2′-Bithiophen]-5-yl)-3- 86% x x x 174 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 19 3-Phenyl-2-(5-(pyridin-2- 72% x x x 175 yl)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1- 20 2-(5-(Furan-2-yl)thiophen-2-yl)-3- 64% x x x 176 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 21 2-(5-(2-Methylthiazol-4- 68% x x x 177 yl)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2- 22 3-(4-Fluorophenyl)-2-(5- 80% x x x 120 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 23 3-(2-Fluorophenyl)-2-(5- 93% x x x 137 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 24 6-Methoxy-2-(5-methylthiophen-2- 89% x x x 161 yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2- 25 6-Fluoro-2-(5-methylthiophen-2- 70% x x x 162 yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2- 26 7-Fluoro-2-(5-methylthiophen-2- 80% x x x 163 yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2- 27 3-(4-Bromophenyl)-2-(5- 80% x x x 177 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 28 3-(3-Bromophenyl)-2-(5- 91% x x x 178 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 29 3-(4-Chlorophenyl)-2-(5- 89% x x x 180 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 30 3-(3-Chlorophenyl)-2-(5- 91% x x x 181 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 31 3-(2-(Methylthio)phenyl)-2-(5- 79% x x x 183 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 32 3-(2-Chlorophenyl)-2-(5- 92% x x x 182 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2- 33 6-Iodo-2-(5-methylthiophen-2-yl)- 92% x 199 3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-3- 34 6-fluoro-2-(5-(2-methylthiazol- 36% x x x 121 4-yl)thiophen-2-yl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)- one

Synthesis of the compounds of general formula (I) for which R⁴ is a methyl radical:

Protocol: a solution of N—H tetrahydroquinazolin-4-ones (1 equiv.) in anhydrous THF (0.5M) is added, dropwise, at 0° C., to a suspension of NaH (1.5 equiv.) in anhydrous tetrahydrofuran (0.3M). After 30 min, iodomethane (1.1 equiv.) is added dropwise. After 10 minutes of reaction, the solution is heated to room temperature and the reaction mixture is stirred for 3 h. The reaction is stopped by adding a saturated solution of NaHCO₃. The aqueous phase is extracted with CH₂Cl₂ (3×50 ml). The organic phases are combined and then washed with a 1M solution of HCl (2×10 ml), dried over anhydrous Na₂SO₄, filtered and concentrated on a rotary evaporator. Purification by silica gel chromatography provides the expected compounds in the form of solids.

TABLE III Molecule Compound Name Yield LC/MS ¹H ¹³C RN-1- 35 1-Methyl-2-(5-methylthiophen-2- 85% starting x x x 181 yl)-3-phenyl-2,3- from RN-1-001 dihydroquinazolin-4(1H)-one RN-1- 36 1-Methyl-3-pheny1-2-(5- 69% starting x x x 186 phenylthiophen-2-yl)-2,3- from RN-1-069 dihydroquinazolin-4(1H)-one RN-1- 37 1-Methyl-3-phenyl-2-(5-(pyridin- 97% starting x x x 192 2-yl)thiophen-2-yl)-2,3- from RN-1-101 dihydroquinazolin-4(1H)-one RN-1- 38 1-Methyl-2-(5- 91% starting x x x 196 (methylthio)thiophen-2-yl)-3- from RN-1-077 phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1- 39 2-([2,2′-Bithiophen]-5-yl)-1- 95% starting x x x 197 methyl-3-phenyl-2,3- from RN-1-080 dihydroquinazolin-4(1H)-one RN-2- 40 2-(5-(Furan-2-yl)thiophen-2-yl)- 97% starting x x x 001 1-methyl-3-phenyl-2,3- from RN-1-104 dihydroquinazolin-4(1H)-one RN-2- 41 2-(5-Ethylthiophen-2-yl)-1- 84% starting x x x 005 methyl-3-phenyl-2,3- from RN-1-068 dihydroquinazolin-4(1H)-one RN-2- 42 1-Methyl-2-(5-(2-methylthiazol- 83% starting x x x 015 4-yl)thiophen-2-yl)-3-phenyl- from RN-1-105 2,3-dihydroquinazolin-4(1H)-one RN-2- 43 2-(5-Bromothiophen-2-yl)-1- 85% starting x x x 016 methyl-3-phenyl-2,3- from RN-1- dihydroquinazolin-4(1H)-one 100 RN-2- 44 1-Methyl-3-phenyl-2-(5- 91% starting x x x 019 (phenylthio)thiophen-2-yl)-2,3- from RN-2- dihydroquinazolin-4(1H)-one 016 RN-2- 45 2-(5-(3,4- 88% starting x x x 029 Dimethoxyphenyl)thiophen-2-yl)- from RN-2- 1-methyl-3-phenyl-2,3- 016 dihydroquinazolin-4(1H)-one RN-2- 46 1-Methyl-2-(5-(3- 90% starting x x x 032 nitrophenyl)thiophen-2-yl)-3- from RN-2- phenyl-2,3-dihydroquinazolin- 016 4(1H)-one RN-2- 47 2-(5-(Furan-3-yl)thiophen-2-yl)- 80% starting x x x 034 1-methyl-3-phenyl-2,3- from RN-2- dihydroquinazolin-4(1H)-one 016 RN-2- 48 Methyl 4-(5-(1-methyl-4-oxo-3- 80% starting x x x 049 phenyl-1,2,3,4- from RN-2- tetrahydroquinazolin-2- 016 yl)thiophen-2-yl)benzoate RN-2- 49 2-(5-(4-Acetylphenyl)thiophen-2- 89% starting x x x 050 yl)-1-methyl-3-phenyl-2,3- from RN-2- dihydroquinazolin-4(1H)-one 016 RN-2- 50 1-Methy1-3-phenyl-2-(5-(3,4,5- 73% starting x x x 053 trimethoxyphenyl)thiophen-2-yl)- from RN-2- 2,3-dihydroquinazolin-4(1H)-one 016 RN-2- 51 1-methyl-2-(5-(4-methyl-3- 76% starting x x x 057 nitrophenyl)thiophen-2-yl)-3- from RN-2- phenyl-2,3-dihydroquinazolin- 016 4(1H)-one RN-2- 52 4-(5-(1-Methyl-4-oxo-3-phenyl- 78% starting x x x 059 1,2,3,4-tetrahydroquinazolin-2- from RN-2- yl)thiophen-2-yl)benzonitrile 016 RN-3- 53 5-(1-Methyl-4-oxo-3-phenyl- 68% starting x 012 1,2,3,4-tetrahydroquinazolin-2- from yl)thiophene-2-carbonitrile RN-2-016 RN-3- 54 3-(2-chlorophenyl)-1-methyl-2- 67% x x x 066 (5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3- 55 3-(2-iodophenyl)-1-methyl-2-(5- 46% x x x 067 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3- 56 3-(2-methoxyphenyl)-1-methyl-2- 28% x x x 068 (5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3- 57 1-methyl-3-(2- 73% x x x 069 (methylthio)phenyl)-2-(5- methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3- 58 3-(2-fluorophenyl)-1-methyl-2-(5- 51% x x x 070 methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3- 59 3-([1,1′-biphenyl]-2-yl)-1-methyl- 74% x x x 089 2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3- 60 1-methyl-2-(5-methylthiophen-2- 65% x x x 098 yl)-3-(2-(phenylsulfonyl)phenyl)- 2,3-dihydroquinazolin-4(1H)-one RN-3- 61 6-fluoro-1-methyl-2-(5-(2- 71% x x x 122 methylthiazol-4-yl)thiophen-2- yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one

II. Measurement of the Protective Activity of the Compounds Against the Toxins on Cells II. A. Experimental Protocol

The compounds were tested either on A549 cells (human pulmonary epithelial cells) or on HeLa cells (human uterin cancer cells), respectively against ricin and against Shiga toxins (Stx1 and/or Stx2). The human cells are cultured at 37° C. in an atmosphere containing 5% CO₂ in 150 cm² culture flasks in DMEM medium (Dulbecco's Modified Eagle Medium) containing 100 U/ml of penicillin and 100 μg/ml of streptomycin. The cells are seeded at a density of 50 000 cells per well in Cytostar-T 96-well plates that have a base into which solid scintillant has been incorporated (FIG. 3). The cells (100 μl in complete DMEM: DMEM+10% of fetal calf serum (FCS) are preincubated or not preincubated with the inhibitors (50 μl; various concentrations, preincubation of 3 h). The complete medium supplemented with toxin (50 variable concentration range) is then added to each well. After incubation for 20 h, the medium (200 μl) is removed and replaced with a leucine-free DMEM medium (Eurobio) containing 10% of FCS and 0.5 μCi/ml of ¹⁴C-leucine (GE). After incubation for 7 h at 37° C., the incorporation of radioactivity by the cells is determined by reading the plates using a Wallac 1450 Microbeta Trilux scintillation counter (PE).

Since these toxins block protein synthesis, the affected cells are no longer capable of incorporating the radiolabeled leucine. On the other hand, the cells treated with inhibitors still synthesize proteins and therefore incorporate the radiolabeled amino acid. Since the cells concentrate the radioelement sufficiently close to the base of the well, this leads to an excitation of the scintillant contained in the plates and results in the emission of photons, detected by the scintillation counter (measurement in counts per minute, cpm). These data are then expressed as percentage of protein synthesis by the cells. The cytotoxicity curves can thus be plotted (R, FIG. 3), without inhibitor (white surface) or in the presence of inhibitor (black surface). The analysis of the data by nonlinear regression makes it possible to estimate the EC₅₀, that is to say the effective concentration for which 50% assimilation of radioactive leucine is observed, which corresponds to 50% of viable cells. The higher the EC₅₀ value, the greater the cell protection since a high concentration of toxin is then necessary in order to generate the same cytotoxicity. It is thus possible to determine the effectiveness of the inhibitors by calculating the ratio of the EC₅₀ values (R, cf. FIG. 3). The higher the value (>1), the greater the protection of the cells.

Results

Table IV below presents the results in the form of a protective index (EC₅₀ compound/EC₅₀ ricin ratio): the higher it is, the more the cells are protected against the action of the ricin (protective effect if >1).

TABLE IV Evaluation of the biological activities of the compounds according to the invention. Molecule Compound R (ricin) R (Stx) Control Retro-2 2.7 25 RN-1-068 7 2.6 120 RN-1-100 9 1.8 27.9 RN-1-148 13 4.2 153 RN-1-173 17 2.8 43 RN-1-174 18 5.6 50 RN-1-175 19 3.1 46 RN-1-176 20 0.7 41 RN-1-177 21 7.3 109 RN-2-162 25 — 133 RN-2-183 31 — 99 RN-2-182 32 — 68 RN-3-121 34 — 295 RN-1-181 35 6.4 80 RN-1-186 36 6.1 29 RN-1-192 37 4.3 111 RN-1-196 38 4.6 60 RN-1-197 39 4.0 36 RN-2-001 40 — 27 RN-2-005 41 6.7 173 RN-2-015 42 8.1 85 RN-2-016 43 4.6 40 RN-2-019 44 3.6 71 RN-2-034 47 4.1 49 RN-3-066 54 — 27 RN-3-067 55 — 25 RN-3-068 56 — 26 RN-3-069 57 — 25 RN-3-070 58 — 25 RN-3-089 59 — 27 RN-3-098 60 — 320 RN-3-122 61 — 40

These assays demonstrate that the tested compounds according to the invention provide better protection against ricin and/or Stx than cyclized Retro-2.

II.B. Alternative Method for Evaluating the Activity of the Compounds According to the Invention Against Shiga Toxin

Table IV above presents the measurement of the inhibitory power of the compounds in the form of a protective index R (EC₅₀ toxin+compound/EC₅₀ toxin ratio; cf. FIG. 4). The higher the value of R, the more the cells are protected against the action of the toxin. More precise additional data (additional table V hereinafter) are provided for the compounds which have indices R close to that of Retro-2 (R close to 25 in the case of Shiga toxin), in order to dispense in particular with the variability of R.

Indeed, the value of R for a given molecule varies according to experiments. It is not an absolute value and R cannot be used to compare the various molecules with one another, unless they were all tested on the same day in the same experiment. This value only makes it possible to compare the activity of a compound with respect to the control (i.e. Retro-2) and to determine whether or not the molecule is more active in Retro-2 at a given concentration. Indeed, the results in table IV are obtained from experiments carried out with a one and only concentration of compound (30 μM).

The results in the additional table V are based on the study of a range of concentration of each of the compounds tested and are more precise since they make it possible to dispense with the value R and to provide an IC₅₀ value which is comparable between all the compounds. IC₅₀ corresponds to the concentration of compound which gives 50% of its inhibitory power. The lower this concentration, the more powerful the inhibitor is.

Protocol and Calculation of IC₅₀

The test on a 96-well plate is the same as that described in part II.A. above. A whole 96-well plate is required in order to calculate the IC₅₀ of each compound.

Six cytotoxicity curves are obtained in the absence and then in the presence of increasing concentrations of the inhibitor. For each concentration (C) of inhibitor, a protection percentage is determined from the value of R calculated by the Prism software with Rmax corresponding to the maximum value of R of the series:

% protection=[(R−1)/(Rmax−1)]×100

The IC₅₀ is then calculated, using the Prism software by nonlinear regression, from a graph on which is reported, for each concentration of compound, the corresponding cell protection percentage (cf. FIG. 5).

Results

TABLE V Molecule Compound IC₅₀(μM) Control Retro-2 27.3 RN-1-100 9 13.7 RN-2-001 40 1.5 RN-3-066 54 8.2 RN-3-067 55 5.4 RN-3-068 56 5.4 RN-3-069 57 3.8 RN-3-070 58 5.5 RN-3-089 59 3.7 RN-3-061 62 12 VP37 63 3-5 VP153 64 <3 VP22 65 1-3 VP104 66 1 KH071-4 67 13 KH093-4 68 4.2 KH112-2 69 11.2

Conclusion

These results show that the compounds tested are all more powerful inhibitors of the cellular effect of Shiga toxin than the Retro-2 compound.

III. Demonstration of the Blocking of the Retrograde Transport Experimental Protocol

The retrograde transport of Shiga toxin subunit B (StxB) for the Golgi apparatus was quantified using a sulfation test described in detail in the literature (Amessou M. et al. Curr. Protoc. Cell. Biol. 2006, Chapter 15: Unit 15.10). The principle is the following: a variant of StxB, called StxB-Sulf₂, which carries a tandem of protein sulfation recognition sites, is internalized in the presence of ³⁵SO₄ ²⁻. Once StxB-Sulf₂ reaches the Golgi apparatus, the sulfotransferases located in the Golgi apparatus catalyze the transfer of the radioactive sulfate onto StxB-Sulf₂. After cell lysis, immunoprecipitation and gel electrophoresis, the [³⁵S]-StxB-Sulf₂ can be detected and quantified by autoradiography. In a previous publication (Stechmann B. et al. Cell 2010, 141, 231-24), it was shown that the retrograde transport of cells treated with Retro-1 or Retro-2 was decreased by 90% under certain experimental conditions.

Results

Table VI indicates, for the nontreated cells and the cells treated with various molecules, the measurement of the retrograde transport as a percentage. 100% indicates no effect on retrograde transport, 0% indicates complete blocking of this transport.

TABLE VI Evaluation of the retrograde transport of cells in the presence of compounds according to the invention. Molecule Compound % control DMSO 100 Retro 2 36.9 RN-1-068 7 13.5 RN-1-148 13 13.1 RN-1-173 17 22.8 RN-1-174 18 17.1 RN-1-175 19 10.7 RN-1-176 20 6.5 RN-1-177 21 0.0 RN-1-186 36 7.1 RN-1-192 37 10.3 RN-1-196 38 18.2 RN-1-197 39 6.2 RN-2-001 40 5.3 RN-2-005 41 0.0 RN-2-015 42 0.0

CONCLUSION

The compounds above show a marked retrograde transport blocking activity, greater than that of Retro-2, which can be explained either by good affinity for the target and/or good internalization into the cell, or by good stability of these compounds in a biological medium. 

1. A compound of formula (I):

wherein: R¹ represents a hydrogen atom, a halogen atom or an alkoxy radical having from 1 to 3 carbon atoms; R² represents a phenyl ring, optionally substituted with: a phenyl radical, a halogen atom, an —SO₂-phenyl group or an —S—X or —O—X group, X being an alkyl radical having from 1 to 4 carbon atoms, an alkoxy having from 1 to 4 carbon atoms or a PEG of formula —(CH₂—CH₂—O)_(n)—R with n being 1 to 10, and R is a hydrogen atom or a methyl radical or a —CO—Y or —CO—O—Y group, Y being a hydrogen atom, an alkyl radical having from 1 to 4 carbon atoms, a phenyl ring or an allyl (—CH₂—CH═CH₂) group; R³ represents a thiophene ring substituted on C5′ of the thiophene, the quinazolinone ring being bonded to C2′ of the thiophene, with: an alkyl radical having from 1 to 3 carbon atoms; a halogen atom; a phenyl radical optionally substituted with an alkoxy radical having from 1 to 3 carbon atoms, a —CN group, an —NO₂ group or a —COX or —COOX group with X an alkyl radical having from 1 to 4 carbon atoms, or a combination of these substituents; an —SY group, Y being an alkyl radical having from 1 to 4 carbon atoms or a phenyl radical; a —CN group; a —CH₂—N₃ group; an aromatic heterocycle having 5 or 6 atoms, optionally substituted with at least one alkyl radical having from 1 to 3 carbon atoms, a —CH₂—N₃ group, or both; R⁴ represents a hydrogen atom or a methyl radical; and with the exclusion of 3-(4-chlorophenyl)-2-(5-methylthiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one and of the compound such that R¹ is a hydrogen atom, R² a phenyl radical, R³ a 5-methylthiophen-2-yl radical and R⁴ a hydrogen atom.
 2. The compound of claim 1, which is selected from the group consisting of Molecule Compound Name RN-1-068 7 2-(5-Ethylthiophen-2-yl)-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1-100 9 2-(5-Bromothiophen-2-yl)-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1-148 13 3-Phenyl-2-(5-phenylthiophen-2-yl)-2,3-dihydroquinazolin- 4(1H)-one RN-1-149 14 3-([1,1′-Biphenyl]-4-yl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-162 16 8-Methyl-2-(5-methylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-173 17 2-(5-(Methylthio)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-174 18 2-([2,2′-Bithiophen]-5-yl)-3-phenyl-2,3-dihydroquinazolin- 4(1H)-one RN-1-175 19 3-Phenyl-2-(5-(pyridin-2-yl)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-176 20 2-(5-(Furan-2-yl)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-177 21 2-(5-(2-Methylthiazol-4-yl)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-120 22 3-(4-Fluorophenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-137 23 3-(2-Fluorophenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-161 24 6-Methoxy-2-(5-methylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-162 25 6-Fluoro-2-(5-methylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-163 26 7-Fluoro-2-(5-methylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-177 27 3-(4-Bromophenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-178 28 3-(3-Bromophenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-181 30 3-(3-Chlorophenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-183 31 3-(2-(Methylthio)phenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-182 32 3-(2-Chlorophenyl)-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-199 33 6-Iodo-2-(5-methylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-3-121 34 6-Fluoro-2-(5-(2-methylthiazol-4-yl)thiophen-2-yl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-1-181 35 1-Methyl-2-(5-methylthiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-186 36 1-Methyl-3-phenyl-2-(5-phenylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-192 37 1-Methyl-3-phenyl-2-(5-(pyridin-2-yl)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-1-196 38 1-Methyl-2-(5-(methylthio)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-1-197 39 2-([2,2′-Bithiophen]-5-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-001 40 2-(5-(Furan-2-yl)thiophen-2-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-005 41 2-(5-Ethylthiophen-2-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-015 42 1-Methyl-2-(5-(2-methylthiazol-4-yl)thiophen-2-yl)-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-2-016 43 2-(5-Bromothiophen-2-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-019 44 1-Methyl-3-phenyl-2-(5-(phenylthio)thiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-2-029 45 2-(5-(3,4-Dimethoxyphenyl)thiophen-2-yl)-1-methyl-3-phenyl- 2,3-dihydroquinazolin-4(1H)-one RN-2-032 46 1-Methyl-2-(5-(3-nitrophenyl)thiophen-2-yl)-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-034 47 2-(5-(Furan-3-yl)thiophen-2-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-049 48 Methyl 4-(5-(1-methyl-4-oxo-3-phenyl-1,2,3,4- tetrahydroquinazolin-2-yl)thiophen-2-yl)benzoate RN-2-050 49 2-(5-(4-Acetylphenyl)thiophen-2-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one RN-2-053 50 1-Methyl-3-phenyl-2-(5-(3,4,5-trimethoxyphenyl)thiophen-2- yl)-2,3-dihydroquinazolin-4(1H)-one RN-2-057 51 1-methyl-2-(5-(4-methyl-3-nitrophenyl)thiophen-2-yl)-3- phenyl-2,3-dihydroquinazolin-4(1H)-one RN-2-059 52 4-(5-(1-Methyl-4-oxo-3-phenyl-1,2,3,4-tetrahydroquinazolin-2- yl)thiophen-2-yl)benzonitrile RN-3-012 53 5-(1-Methyl-4-oxo-3-phenyl-1,2,3,4-tetrahydroquinazolin-2- yl)thiophene-2-carbonitrile RN-3-066 54 3-(2-Chlorophenyl)-1-methyl-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-067 55 3-(2-Iodophenyl)-1-methyl-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-068 56 3-(2-Methoxyphenyl)-1-methyl-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-069 57 1-Methyl-3-(2-(methylthio)phenyl)-2-(5-methylthiophen-2-yl)- 2,3-dihydroquinazolin-4(1H)-one RN-3-070 58 3-(2-Fluorophenyl)-1-methyl-2-(5-methylthiophen-2-yl)-2,3- dihydroquinazolin-4(1H)-one RN-3-089 59 3-([1,1′-Biphenyl]-2-yl)-1-methyl-2-(5-methylthiophen-2-yl)- 2,3-dihydroquinazolin-4(1H)-one RN-3-098 60 1-Methyl-2-(5-methylthiophen-2-yl)-3-(2- (phenylsulfonyl)phenyl)-2,3-dihydroquinazolin-4(1H)-one RN-3-122 61 6-Fluoro-1-methyl-2-(5-(2-methylthiazol-4-yl)thiophen-2-yl)- 3-phenyl-2,3-dihydroquinazolin-4(1H)-one RN-3-061 62 2-(5-(Azidomethyl)thiophen-2-yl)-1-methyl-3-phenyl-2,3- dihydroquinazolin-4(1H)-one VP37 63 2-(5-(2-(Azidomethyl)thiazol-4-yl)thiophen-2-yl)-1-methyl-3- phenyl-2,3-dihydroquinazolin-4(1H)-one VP153 64 2-(5-(2-(Azidomethyl)thiazol-4-yl)thiophen-2-yl)-6-fluoro-1- methyl-3-phenyl-2,3-dihydroquinazolin-4(1H)-one VP22 65 3-(2-Benzoylphenyl)-1-methyl-2-(5-(2-methylthiazol-4- yl)thiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one VP104 66 3-(2-Benzoylphenyl)-6-fluoro-1-methyl-2-(5-(2-methylthiazol- 4-yl)thiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one KH071-4 67 Allyl 2-(1-methyl-2-(5-methylthiophen-2-yl)-4-oxo-1,4- dihydroquinazolin-3(2H)-yl)benzoate KH093-4 68 3-(2-(2-Methoxyethoxy)phenyl)-1-methyl-2-(5- methylthiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one, and KH112-2 69 2-(1-Methyl-2-(5-methylthiophen-2-yl)-4-oxo-1,4- dihydroquinazolin-3(2H)-yl)benzoic acid


3. The compound of claim 1, wherein R² is a phenyl ring substituted on its carbon C2″.
 4. The compound of claim 2, which is selected from the group consisting of compounds 23, 31, 32, 54 to 60, 65 to 68, and
 69. 5. The compound of claim 1, wherein R⁴ is a methyl radical.
 6. The compound of claim 2, which is selected from the group consisting of compounds 35 to 68, and
 69. 7. A method for preventing and/or treating disorders induced by toxins with an intracellular mode of action using retrograde transport, the method comprising administering an effective amount of at least one compound of formula (I):

to a subject in need thereof, wherein: R¹ represents a hydrogen atom, a halogen atom or an alkoxy radical having from 1 to 3 carbon atoms; R² is a phenyl ring, optionally substituted with: a phenyl radical, a halogen atom, an —SO₂-phenyl group or an —S—X or —O—X group, X being an alkyl radical having from 1 to 4 carbon atoms, alkoxy having from 1 to 4 carbon atoms; or a PEG of formula —(CH₂—CH₂—O)_(n)—R with n being 1 to 10, and R represents a hydrogen atom or a methyl radical, or a —CO—Y or —CO—O—Y group, Y being a hydrogen atom, an alkyl radical having from 1 to 4 carbon atoms, a phenyl ring or an allyl (—CH₂—CH═CH₂) group; R³ represents a thiophene ring substituted on C5′ of the thiophene, the quinazolinone ring being bonded to C2′ of the thiophene, with: an alkyl radical having from 1 to 3 carbon atoms; a halogen atom; a phenyl radical optionally substituted with an alkoxy radical having from 1 to 3 carbon atoms, a —CN group, an —NO₂ group or a —COX or —COOX group with X an alkyl radical having from 1 to 4 carbon atoms, or a combination of these substituents; an —SY group, Y being an alkyl radical having from 1 to 4 carbon atoms or a phenyl radical; a —CN group; a —CH₂—N₃ group; an aromatic heterocycle having 5 or 6 atoms, optionally substituted with at least one alkyl radical having from 1 to 3 carbon atoms, a —CH₂—N₃ group, or both; and R⁴ represents a hydrogen atom or a methyl radical; with the exclusion of the compound such that R¹ is a hydrogen atom, R² a phenyl radical, R³ a 5-methylthiophen-2-yl radical and R⁴ a hydrogen atom.
 8. The method of claim 7, wherein R² is a phenyl ring substituted on its carbon C2″.
 9. The method of claim 7, wherein R⁴ is a methyl radical.
 10. The method of claim 7, wherein the toxins with an intracellular mode of action are selected from the group consisting of ricin, Shiga toxin and Shiga-like toxins (Stxs) produced by Shigella dysenteriae (Stx) and E. coli (Stx1 and Stx2), cholera toxin (Ctx from Vibrio cholerae responsible for cholera), pertussis toxin (Bordetella pertussis, the agent responsible for whooping cough), subtilase cytotoxin and thermolabile enterotoxin (E. coli).
 11. A pharmaceutical composition or a medicament comprising at least one compound of formula (I) as defined in claim 1, in a pharmaceutically acceptable carrier, wherein said pharmaceutical composition or said medicament is adapted to be administered by an airway route, an oral route, a parenteral route or a local route.
 12. A pharmaceutical composition or a medicament, comprising at least one compound of formula (I) as defined in claim 7, in a pharmaceutically acceptable carrier, wherein said pharmaceutical composition or said medicament is adapted to be administered by an airway route, an oral route, a parenteral route or a local route.
 13. The compound of claim 1, wherein the quinazolinone ring isbonded to C2′ of the thiophene with an aromatic heterocycle selected from the group consisting of a furan, a thiophene, a pyrrole, a pyrroline, a pyrrolidine, a dioxolane, an oxazole, a thiazole, an imidazole, an imidazoline, an imidazolidine, a pyrazole, an isoxazole, an isothiazole, a pyran, a pyridine, a piperidine, a dioxane, a morpholine, a pyridazine, a pyrimidine and a pyrazine ring, optionally substituted with at least one alkyl radical having from 1 to 3 carbon atoms, a —CH₂—N₃ group, or both.
 14. The compound of claim 7, wherein the quinazolinone ring is bonded to C2′ of the thiophene with an aromatic heterocycle selected from the group consisting of a furan, a thiophene, a pyrrole, a pyrroline, a pyrrolidine, a dioxolane, an oxazole, a thiazole, an imidazole, an imidazoline, an imidazolidine, a pyrazole, an isoxazole, an isothiazole, a pyran, a pyridine, a piperidine, a dioxane, a morpholine, a pyridazine, a pyrimidine and a pyrazine ring, optionally substituted with at least one alkyl radical having from 1 to 3 carbon atoms, a —CH₂—N₃ group, or both. 